Definition of femtosecond
: one quadrillionth of a second
First Known Use of femtosecond
Rhymes with femtosecond
microsecond, millisecond, nanosecond, picosecond, yoctosecond, zeptosecond
Seen and Heard
What made you want to look up femtosecond? Please tell us where you read or heard it (including the quote, if possible).